Second Largest Digit in a String — LeetCode 1796 Python Solution

The problem

Given an alphanumeric string s, return the second largest numerical digit that appears in s, or -1 if it does not exist. An alphanumeric string is a string consisting of lowercase English letters and digits.

Example

Input

s = "dfa12321afd"

Output

2

Explanation

The digits that appear in s are [1, 2, 3]. The second largest digit is 2.

Python solution

class Solution:
    def secondHighest(self, s: str) -> int:
        a = b = -1
        for c in s:
            if c.isdigit():
                v = int(c)
                if v > a:
                    a, b = v, a
                elif b < v < a:
                    b = v
        return b

Complexity

Pattern: Hash Map

Trade memory for time: remember what you have seen so the second pass never happens. LeetCode 1796. Second Largest Digit in a String is filed here on both counts: the reference solution below belongs to the algorithm family this hub collects, and LeetCode tags it Hash Table.

The hash map guide has the Python template for the pattern and the 709 LeetCode problems that use it.

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